A heartwarming video made the rounds on national news this month, showing a three-year-old at the moment he heard his father’s voice for the first time.

Grayson Clamp sits in his father’s lap, just prior to hearing his dad’s voice for the first time.

Grayson Clamp, from Charlotte, N.C., was born without the cochlear nerves that would allow him to hear, but a miraculous operation performed by Drs. Craig Buchman and Matthew Ewend at UNC Hospitals gave Grayson a new way to enjoy the once-quiet world around him.

Buchman, professor of otolaryngology and head and neck surgery in UNC’s School of Medicine, is a graduate of the Public Health Leadership Program’s leadership certificate curriculum at the Gillings School of Global Public Health. Ewend is chair of the School of Medicine’s Department of Neurosurgery.

Grayson received the first-ever auditory brain stem implant in a child in the U.S. as part of a Food and Drug Administration clinical trial. The device he received originally was used for patients with deafness due to auditory tumors, which impact hearing. The device is now being considered to help restore hearing in children.

“Seeing him respond, that had a lot of feelings for me,” Buchman said. “I felt like there was a potential that we were affecting and changing the world in some ways.”

“I’ve never seen a look like that,” said Grayson’s father, Len Clamp, referring to the day on which Grayson’s implant was turned on for the first time. “He looked deep into my eyes. He was hearing my voice for the first time. It was phenomenal.”